The present invention relates to security systems having alarm means which are activated in response to signals generated by presence and/or motion detectors in an area to be monitored. More specifically, the invention relates to the addition to such systems of the capability of temporarily muting or disabling the alarm or other indicating device.
It is a common practice to install sensing devices in areas which are to be monitored for security purposes. The sensor(s) may be in the form of conventional presence or motion detectors which are actuated in response to a threshold level of infrared energy emitted by a person, vehicle, etc. in the vicinity of the sensor. The sensing device includes an RF transmitter which sends a signal to a receiver located at the desired monitoring location. The received signal activates an audible and/or visible alarm signal, discernable at the monitoring location.
While such systems serve well to perform the monitoring function intended, there are situations in which the alarm is not needed or wanted. For example, if there is a gardener or other workman in the vicinity of the sensing device, the alarm may be activated many times over a relatively brief time period even though the cause of alarm activation is known. Under such circumstances, it is sometimes the practice to disconnect the alarm unit from the power source by which it is activated, either by unplugging the unit or by operating and on/off button. Although this serves to prevent unwanted activation of the alarm, there is the possibility that power may not be restored to the system after the condition which prompted removal of power has ceased.
The object of the present invention is to provide a security system including one or more sensing devices and transmitters activated by presence or motion of an infrared-emitting body to send a signal to a receiver in order to activate an alarm wherein the alarm may be selectively deactivated and automatically reactivated after a fixed or adjustable time period.
Other objects will in part be obvious and will in part appear hereinafter.